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Friday, November 18, 2011

Extra Giant Planet May Have Dwelled in Our Solar System

Scientists are starting to put a few pieces of the puzzle together about how the solar system works, but they are not yet ready to make the big leap into the fact that all planets were born and spit out of the sun into the solar system, and beyond. lol

Within our solar system, an extra giant planet, or possibly
two, might once have accompanied Jupiter, Saturn, Neptune and Uranus.

Computer models showing how our solar system formed suggested the planets once
gravitationally slung one another across space, only settling into their current
orbits over the course of billions of years.

During more than 6,000 simulations of this
planetary scattering phase, planetary scientist David Nesvorny at the Southwest Research
Institute in Boulder, Colo., found that a solar system that began with
four giant planets only had a 2.5 percent chance of leading to the orbits
presently seen now. These systems would be too violent in their youth to end up
resembling ours, most likely resulting in systems that have less than four
giants over time, Nesvorny found.

Instead, a model about 10 times more likely
at matching our current solar system began with five giants, including a now
lost world comparable in mass to Uranus and Neptune. This extra planet may
have been an "ice giant" rich in icy matter just like Uranus and Neptune,
Nesvorny explained.

When the solar system was about 600 million
years old, it underwent a major period of instability that scattered the giant
planets and smaller worlds, researchers said. Eventually, gravitational
encounters with Jupiter would have flung the mystery world to interstellar space
about 4 billion years ago.

As fantastic as these findings might sound,
a large number of free-floating worlds have recently been discovered in
interstellar space, Nesvorny noted. As such, the ejection of planets from solar
systems might be common.

"The work raises interesting questions about
the early history of the outer solar system," Nesvorny told SPACE.com. "For
example, traditionally, most research was focused on the giant planets, their
satellites, Kuiper belt objects, and their interaction — that's what we have in
the outer solar system now. But how about Mars to super-Earth-size bodies? Have
such objects formed on the outer solar system and were eliminated later? If
not, then why?"

"This is just a beginning," Nesvorny said.
"It will need quite a lot of work to see if there actually was the fifth planet.
I am not fully convinced myself."

Nesvorny's research is detailed online in
the journal Astrophysical Journal Letters.